When that concentration is multiplied by the inhalation volume for an exposure by an individual worker, the average number of spores inhaled (the dose) is computed as follows:

Using the best estimate for the dose–response relationship (in the exponential dose-response model), the risk (per individual exposed) is computed to be:

This computation suggests that all individuals so exposed should have contracted inhalation anthrax. However, it is obvious that several parameters and assumptions have gone into the production of this point estimate. If the uncertainties in each input were considered, what would be the estimated confidence limit for the number of persons who could have become ill?

There are two approaches to this assessment. In the first approach, all of the point estimates in Table E-1 are used and, in addition, an “effectiveness factor”